84z28h.o.

Alright, so let me kind of start at square one.

I have a 1984 Z28 H.O. and the carb has no choke assembly whatsoever. The car idles at 1500rpm even if I mess around with the idle screw on the drivers side of the carb. When it is warmed up, it STILL idles at 1500.

I was told it could be a vacuum leak...which it might very well be, since there is an open vacuum port that is supposed to go to the choke.

But my problem is that when I turn the car off, and even take the key out...my engine still wants to run. It doesn't stay on fully, but it sputters and sometimes even backfires once or twice then finally cuts off.

I've went as far as putting the car in first gear and popping the clutch just to make the car die so it wouldn't do that hideous PUT PUT PUT PUT POW. Does anyone have any idea what it could be? It seems like it's getting too much fuel somehow, but I don't know.

Sonix

iTrader: (1)

Geez, you already know what the problem is, why not go and fix it rather than spending your time posting? Fix the vacuum leak. That's all there is to it.

Which carb is it on there?
A vacuum line that goes to the choke (???) might have full vacuum, ie. not ported. I have no idea what carb this is though...
CAP OFF ALL VAC LINES! Any not used, just buy one of those packs of vacuum caps and throw 'em on. That'll lower your idle speed first of all.

After that you can see if it still runs on, but I have a feeling it won't.

WhiteHawk

Pull the main ignition wire off as it is sputtering...if she is still running then something is making spark. Either a combo of compression ignition and hot carbon.

Do this, goto a GM dealer and get a bottle of "Top Engine Cleaner". This stuff rocks. You pour in half the bottle slow, then dump the rest to flood it and kill it. Then let it sit...start here up and you have a cleaner engine...BE SURE TO DO IT OUTSIDE, IT WILL SMOKE LIKE NO OTHER.

84z28h.o.

Sonix, I actually do not know what the problem is. I don't really think that a vacuum leak would cause it to still run after I turn the car off. I don't know how it would make it still run.

WhiteHawk, I used Seafoam in the carb a little while back and it smoked for a good 7 minutes...good stuff.

I am going to install a new carb today, we'll see if it takes care of it.

Oh, by the way it is a Rochester Quadrajet E4ME that is on the car right now...going to replace with the same carb.

Sonix

iTrader: (1)

What happened to the choke assembly on your Q-jet? someone hacksawed it off?
I'd first cap off all the lines on that carb and see what happens.

A vacuum leak would make it keep running for a little bit. Another source of dieseling is a hot combustion chamber, seafoam will clean it out as mentioned, and might help. Another is to see if the timing is retarded too far.

zacharyhorn

iTrader: (1)

Does it run hot? I vote for the timing being too retarded. Advance your distributor.

84z28h.o.

Yes, when I bought the car, the complete choke assembly was missing. I just installed a rebuilt Quadrajet E4ME....the choke works, I suppose...it was idling between 2000 and 2250 or so. The butterfly opened up, but it was still idling high.

I heard that there is supposed to be some green wire connected to the choke somewhere, but I have no idea where it goes, or what the wire even looks like.

I took the car out for a spin, and after a little while it would get to the point where I'd be stopped, the car would idle at 2000 for a few seconds, drop down to 1500, then idle at 950.

Got home, it was idling at 950 and I turned the car off....it still sputtered and everything. All of the vacuum lines are connected on the carb and there are two that are unused, one in front and one in back and those have caps on them.

Also, this new Q-jet runs different than my old one. The throttle is more peppy....at only half throttle, it gets up and goes. But also, it seems that it doesn't make as much power as the old carb until I get into 3rd gear. Maybe it just needs to be tuned.

I am planning on getting a new distributor, wires, and plugs so maybe that will help with the sputtering when I turn the car off.

The car doesn't run hot....it stays right at or a few degrees above 200. I have a 195 thermostat installed.

zacharyhorn

iTrader: (1)

What is your timing at now?

84z28h.o.

I'm not sure what the timing is set at. I don't have a timing light.

Could the timing just retard somehow without me touching the distributor? Because when I first got the car, it would turn off fine. Then not too long after I got it, all the problems of the car became apparent.